That the sound difference is such that it can be captured with any of the setups pictured in the paper is impossible. There are systems designed for frequency isolation that do megahertz sampling rates which you could convince me are capable of reading the 1's and 0's out of a 286. The frequencies of modern electronics that is simply not possible.

They are claiming to pick up a rather large algorithm change in code that runs for dozens of milliseconds to extract a single bit. A loop taking a bit over 26 vs. a bit over 28 microseconds in the example (or something reasonably close to that description). Why would this need such high-end equipment to pick up?